Lumpy Bracket

IUCN Red List

not listed

NatureServe

NNR - Unranked

Minnesota

not listed

Lumpy Bracket (Trametes gibbosa) is an exotic, medium-sized to large, bracket fungus. It is native to Europe and Asia. It was previously included in Trametes elegans, and printed field guides and most online resources still refer to it by that name. It was first identified in North America in 2007 when cultures from Pennsylvania and Quebec were compared with cultures from the Czech Republic. It is believed to have been introduced accidentally by either imported wood or nursery stock. It now occurs throughout the United States and southern Canada east of the Great Plains and in the Pacific Northwest.

Lumpy Bracket is found from spring through fall, alone or in groups but not clustered (gregarious), on the dead wood of hardwood logs and stumps. It obtains its nutrients from decayed wood (saprobic). It is an annual fungus, only producing spores for one season, but its leathery brackets are extremely durable and often persist on the wood throughout the winter and into the following year.

The cap is 1½″ to 8″ (4 to 20 cm) wide, 1″ to 3½″ (2.5 to 9.0 cm) deep, ⅝″ to 2″ (1.5 to 5.0 cm) thick, semicircular or kidney-shaped, and flat above but convex below (planoconvex). While usually appearing as a shelf-like bracket, it is sometimes effused-reflexed, growing as part shelf and part flat crust. In these instances, especially in younger growth, the pore surface is decurrent, stretching several inches down the bark from the point of attachment while the cap remains relatively small.

When young, the fungus is whitish and the texture is corky. The margin is rounded and often yellowish to brownish. The upper surface is dry with concentric zones of soft, short, woolly, matted hairs (tomentose) alternating with hairless (bald) zones. The zones may be distinct or barely discernible. As the bracket grows outward from the tree, it tends to thicken and swell at the base where it attaches to the wood, creating a distinct “hump.” This is the feature that gives the fungus its species epithet gibbosa, which means “humped” or “gibbous.” As it ages, it becomes grayish or brownish and the margin is sharply angled (acute). The surface often becomes partially covered with green algae, especially in the hairy zones, which can create a striped appearance.

The underside (pore surface) is whitish to brownish with 1 to 2 pores per 1⁄32″ (1 mm). The pores are thick-walled and mostly 1⁄16″ to 5⁄16″ (2 to 8 mm) deep, up to ⅝″ (15 mm) deep in older “humps.” They are usually elongate, radiating outward from the point of attachment, and 1⁄32″ to 3⁄16″ (1 to 5 mm) long, but there are occasionally some longer, maze-like pores. The pore surface may bruise yellow to pinkish or brownish or not bruise at all. On older specimens it is often bug-eaten.

The spore print is white.

Similar Species

Hardwoods

Season

Spring through fall